1. Field of the Invention
This invention relates to a spring metal terminal for establishing a contact with the opposite sides of a circuit panel and more particularly to an edge stamped contact terminal which is spring biased upon insertion of a circuit panel between opposed arms.
2. Description of the Prior Art
Electrical connectors used to establish contact with surface pads on a circuit panel substrate can employ terminals of two types. Terminals can be formed by stamping a blank configuration and then bending or forming the terminals to a final shape. Terminals of this type are shown in U.S. Pat. No. 4,557,548. Other connectors employ terminals which are stamped from a blank in their final configuration. U.S. Pat. No. 3,848,952 discloses a stamped contact suitable for establishing a zero insertion force interconnection to surface pads on a printed circuit board. The terminals shown in U.S. Pat. No. 4,577,922 also appear to be stamped in their final configuration. Stamped terminals of this type can be used in a connector of the type shown in U.S. Pat. No. 4,575,172. These latter patents disclose terminals in which a circuit panel substrate is first positioned between contact points and then subsequent movement is required to bring the surface pads into engagement with contact points on the terminals. Other edge stamped contact terminals of this general type are shown in U.S. Pat. Nos. 4,136,917; 4,354,729; 4,370,0174; and 3,426,313. Other printed circuit board connectors employing edge stamped terminals do not require such zero force insertion but instead permit a printed circuit board to be inserted edgewise directly between opposed contact surfaces. Examples of connectors of this type are shown in U.S. Pat. No. 3,075,167 and U.S. Pat. No. 3,270,313. A connector having separate terminals on opposite sides of a printed circuit board is shown in U.S. Pat. No. 4,619,495. Except for minor lead-in angles, these last mentioned patents can require a relatively high insertion force since the terminals are being flexed in the plane of the blank contact. In addition to high mechanical forces required to mate a printed circuit board with connectors of this type, high normal forces could cause damage to the connectors themselves.
U.S. Pat. No. 4,619,495 and U.S. Pat. No. 4,025,147 disclose printed circuit board connectors in which the printed circuit board insertion force would not appear to be excessive because the terminals themselves are quite thin. Typically, insertion forces would be less for relatively thin terminals of this type and for stamped and formed terminals such as those shown in U.S. Pat. No. 4,557,548. The instant invention, however, is directed to a terminal for a printed circuit board edge connector which employs terminals edge stamped from a blank which can be wrapped around the edge of a circuit panel to establish contact with pads on opposite sides of the circuit panel and which can generate high normal forces on a close centerline spacing of the type characterized by edge stamped terminals but which allow the contacts to be deflected in a manner such that the insertion force is comparatively low. A connector in which this terminal can be employed is disclosed in a copending application filed on even date entitled "High Density Circuit Panel Socket" Ser. No. 006,848, 1/27/87.